Electric plug and receptacle



March 18, 1941*.

C. J. SAUNDERS ELECTRIC 'rwa- AND RECEPTACLE Filed July 19', 1953 k FIG. 1.

INVENTOR. Charles J. Saunders Patented 18, 1941 UNITED STATES ELEc'rmc PLUG AND nEcErTAcLE Y Charles J. Saunders, Los w s, Calif.

Application Ju y 19.

2 Claims.

My invention relates to electrical connectors and has particular reference to a plug and receptacle adapted to readily permit connection of portable electrical appliances to an electric supply circuit.

To provide for the ready connection of portable electrical appliances to supply circuits in homes. stores or other buildings, it is the usual practice to provide the appliances with a flexible electric cable to one end of which is secured a connector plug having metal terminals thereon adapted to be inserted into terminal openings in a receptacle which in turn is permanently and stationarilylocated in the building and is permanently connected to the supply circuit or wiring within the building or into the terminal openings of an adaptor which is screwed into a socket,

The ordinary construction of such plugs and receptacles is such that the prongs or metal terminals project from a handle portion in such a manner as to permit them to be inserted into predetermined terminalopenings in the receptacle, making it necessary to accurately align the ends of the plug terminals with the reception openings before the plug may be inserted. It'frequently occurs that connection of the appliances must be made in the dark, or the location of the receptacle is such that it is impossible to see the terminal openings therein so that it is necessary to make several attempts to align the plug terminals with the openings before the connections may be completed.

It is therefore an object of my invention to provide a plug and receptacle so constructed that the front surface of the receptacle constitutes a guide for the plug, automatically aligning the axis of the plug with the center of the-receptacle.

It is another object of my invention to provide a plug and receptacle of the character set forth 4 in the preceding paragraph wherein the mere pressing of the plug-against the front face of the receptacle will center the plug with the receptacle, making it necessary only to turn the plug in its centered position to accurately align the receptacle openings with the plug terminals.- Another object of my invention is to provide a plug and receptacle of the character set forth wherein the plug is provided with an outwardly projecting guide stem and in which the receptacle is provided with an axially aligned guide bore for receiving the stem to constitute a guide for the insertion of the plug in the receptacle and in which terminal openings are so arranged with respe t to the guide bore that a slight twistlns movement of the plug after the stem has been 1938, Serial No. 219,991

insertion of the plug into electrical contact therewith. Other objects and advantages of my invention will be apparent from a study of the following specifications, read in connection with the accompanying drawing, whereinm Fig. 1 is a perspective view of the receptacle construction, in accordance with my invention, applied to the usual type of wall receptacle installation.

Fig. 2 is a perspective view of a connector plug constructed in accordance with my invention and g iiiapted for use with the receptacle shown Fig. 3 is a vertical sectional view takenalong line III-III of Fig. 1 showing the internal construction of the wall receptacle and showing a plug inserted therein.

Fig. 4 is a side elevational view of the receptacle body sh'own'in Fig. 3. a

Fig. 5 is a detail sectional view taken along line V-V of Fig. 4.

Fig. 6 is a detail sectional view taken along line VI-VI of Fig. 4.

Fig. 7 is a detail sectional view .of the plug constructed in accordance with my invention, the

section being taken along line VII-Vl1 of Fig. 2.

Referring to the drawing I have illustrated, particularly in Fig. 3, a wall receptacle A constructed in accordance with my invention adapted to be mounted in the conventional junction box I employed in the ordinary wiring of buildings. The junction box I may be a metal box of the conventional type secured immediately to the rear of the surface of a wall 2 and to which a conduit or other form of protective sheathing 3 may be coupled which carries conductor wires 4 and I for supplying electric current to the recep-'- tacle A.

The receptacle A includes a body member 8 illustrated as comprising a cylindrical piece of suitable insulating material adapted to be secured to a supporting strip 1 as by means of pressing the same into a circular opening 8 in the strip and eitherholding the same therein a radially extending flange l3 preferably adapted v to rest against the outer surface of the supporting strip I so that a relatively large diameter cone-shaped-depression i4 may be formed in the outer face of the body 6, the apex of the cone leading into a cylindrical bore 45 disposed along the central axis of the body 3. A pair of oppositely disposed radial slots l3 and I1 extend for a considerable distance from the front face of the body 6 and communicate with the central bore ii to provide terminal openings adapted to receive plug terminals formed upon and constituting part of a plug connector B to be hereinafter more fully described.

The receptacle terminals may be provided, illustrated herein as comprising short strips of suitable metal i3 and I9, each of the terminals l8 and I9 having an elongated body portion, one end of which is secured as by a screw 20 to the outer surface of the body 9 near the extreme rear end of the body so that the engaging end 2| of the terminal strip 19 may flex through relatively great limits without permanent distortion of the strip. The engaging end of the strips l8 and I9 are illustrated as being bent about a relatively sharp radius to present a smooth curve to the plug terminals, the engaging ends 2| of the strips l3 extending into radial extensions 22 of the recesses i6 and i1 respectively.

By referring particularly to Fig. 5 it will be noted; that the strips 13 and I3 are providedwith lateral extensions 23 through which is threaded a screw 24 and between which the ends of the wires 4 and 5 may be clamped to make connection therewith. The receptacle so constructed and assembled upon its strap I may be secured to the box I with the outer surface of the strap 1 approximately flush with the wall surface 2' and the usual face-plate 25 may be attached in the conventional manner by means of screws 26.

The plug B, which may be used with my receptacle, may comprise a handle or body portion constructed of complementary halves 21 and 23, one of these halves including recesses 29 and 3!! disposed upon diametrically opposing sides of a cylindrical stem-like portion 3| which projects forwardly of that half of the body. Secured as by means of screws 32 to this half of the body portion are a pair of strips of metal 33 and 34 which extend through the recesses 29 and 30 and along the forwardly projecting stem 3|, the strips 33 and 34 constituting the plug terminals l3 and I9. While the shape of the strips 33 and 34 is not material, I prefer to construct them of strips of relatively heavy brass or similar material and The inner ends of the strips 33 and may have threaded holes therein to receive wire clamping screws 31 by which electrical conductors 33 and 39 may be connected to the plug terminals. such conductors extending into the rearward end of the plug B through semi-cylindrical recesses 40 formed in the complementary members 21 and 23. The rearward ends of the members 21 and 23 may be flattened as indicated at 4| to provide finger grips bywhich the plug may be readily handled, while th forward ends of the members Hand 23 are preferably constructed as half cones so that when these members are assembled together and the plug is inserted into the receptacle as shown in Fig. 3, the cone-shaped outer surface of the plug will fit snugly within the named surface of the receptacle body 3., I

The extreme outer end of the stem 3| may be rounded off as indicated at 42 to present a smooth surface for engagement with the coned surface I 4 of the receptacle so that in inserting the plug into the receptacle all that is necessary is to project thestem against the coned surface of thereceptacle and, by reason of the coned.

surface, the plug stem will automatically find the central or axlal bore l5 and thus, irrespective of whether the person can view the receptacle, the alignment of the plug and receptacle may be readily accomplished. The plug terminals 33 and 34 extend on each side of the stem 3i as keys to be inserted in the keyhole recesses i3 and I1 so that once the stem has been aligned in the bore l5, it is only necessary to press the plug toward the receptacle and t9 rotate it until the key-like terminals enter the keyhole" slots l6 and I1. Then the plug may be pressed inwardly of the receptacle with assurance that the plug terminals will be aligned with and will engage the receptacle terminals I8 and l9.

The construction of the receptacle as hereinbefore described, is relatively inexpensive, since the body portion may readily'be formed by any of the well known die molding methods and the terminal strips I3 and I9 may be readily secured thereto in the well known or conventional manner. Likewise the plug may be manufactured inexpensively by die molding the body halves 21 and 23 and merely assembling the terminal I strips 33 and 34 thereon. It will be noted that the terminal strips may be secured in place by a single screw for each of them, and that their extension along and in contact with the stem 3| will reinforce these strips, opposing distortion of them due to pressure exerted by the receptacle terminals i3 and I9. The rounded ends of the receptacle terminals l8 and I9, received in the depressions 36 of the plug terminals, will tend to hold the plug 'in p1ace within the receptacle and avoid accidental removal therefrom.'

It will therefore be apparent that I have provided a simple and inexpensive receptacle, the exposed face of which constitutes a funnel-like guiding face which will tend to, centralize a plug attempted to be inserted therein, and that I have provided an equally inexpensive construction of aplug having a projecting centralizing stem thereon which will assist in locating the plug in the correct axial alignment with the receptacle and will assist in guiding the terminals P of the plug into engagement with the terminals of the receptacle without the necessity of being able to view the receptacle when the plug is being inserted therein.

While for purposes of illustration and descripaasasss tion herein, I have shown my plug and receptacle each with two terminals thereon, it will be understood by those skilled in this art that a greater number of radial slots it and it may be provided, disposed about the central bore is while a similar greater number of terminal strips and ii -i may be provided upon the plus. perznitting a three or more wire connection to be notch in the outer face of each of said terminals;

and a receptacle including a body member having a bore therein for receiving said stem, a coneshaped' depression formed in the front face of said body member with the axis thereof aligned with the axis of said bore for receiving said stem and guiding said plug into alignment with said receptacle, the angle of said cone-shaped depression being substantially equal to the angle at which the ends of said terminals are beveled whereby scratching of the surface of said coneshaped depression by the ends of said terminals is obviated, a plurality of radially disposed recesses in said body member disposed about said bore and communicating with the surface of said cone-shaped depression and with said bore l for receiving said terminals, horizontally disposed resilient terminal connector strips secured to the exterior of said body member and having transversely disposed contacting portions thereof extending into said racemes to enter said plug terminal notches, said contacting portions comprising semi-cylindrical portions formed by bending said strip back upon itself on a radius substantially longer than the thickness oi said strip.

2. An electric terminal connector comprising in combination: a receptacle including a body portion having a cone-shaped depression formed in the front face thereof, a cylindrical bore in said body portion extending from the apex oi said cone-shaped depression and disposed in alignment with the axis thereof, means on said body portion defining a transversely extending Opening through said bod portion intersecting said bore at a point spaced from said coneshaped' depression, a pair of electric terminals comprising thin strips of resilient metal secured to the exterior of said body extending inwardly into said opening from opposite ends thereof and terminating in a rounded portion formed by bending said resilient material into a semicylindrical shape, and a pair of contact receiving slots extending radially outward from opposite sides of said bore extending into communication with the surface of said cone-shaped depression and intersecting said opening; and a plug insertable in said receptacle including a substantially cylindrical handle member, a forwardly projecting cylindrical stem secured to said handle member for reception in said bore, and a pair of electric contact strips carried by said handle member comprising thin strips of metal disposed on edge on opposite sides of said stem for reception in said contact receiving slots when said stem is inserted in said bore, means on said handle securing said contact strips thereto in engagement with said stem, each of said cont-act strips having a beveled end for engaging said receptacle terminals to wedge the same apart and permit said contact strips to be in- 'serted therebetween, each of said contact strips also including a. semi-circular notch for receiving the rounded end of said receptacle terminals to resist movement of said plug out of said receptacle.

CHARLES J. SAUNDERS. 

